204 CRUSTACEA, 
the imaginary line which unites the external orbital an- 
gles, in two furrows that border the anterior part of the 
mesogastric area. The upper margins of the orbits are con- 
cave, their external angles straight and the lateral margins 
of the cephalothorax, which are almost straight and di- 
verge backwards, are distinctly cristate. These lateral mar- 
gins like also the orbital margins and those of the front, 
are entire, nowhere dentate, and both a supra-ocular 
and an epibranchial tooth are wanting. The so- 
mewhat convex, glabrous upper surface presents about the 
same remarkable sculpture as is found in Petrol. mossam- 
bicus, though not exactly on the same manner, Like as 
in the Afrika-species, the cervical suture is followed a little 
more backwards by another one, parallel with the former, 
and the two epigastrical lobes are tuberculiform, whereas 
the mesogastric region presents on either side a small tu- 
bercle, a few granules being placed before them. No tu- 
bercles, however, are observed on the lateral parts of the 
gastric region. Six symmetrically arranged prominences are 
found on the cardiacal region, of which the two anterior 
pairs are separated from one another by a rather broad 
transverse groove, the two posterior by a very narrow 
one. Three or four tubercles are observed, on either side, 
between the two cervical sutures. The posterior cervical 
suture is bordered by some oblong prominences and many 
short transverse ridges or elevations are found on the 
branchial regions, of different size, and which become smal- 
ler towards the lateral margins of the cephalothorax and 
which are so small on the intestinal region, that they may 
only be recognized there by means of a magnifying-glass. 
The median triangular part of the terminal segment of 
the smooth abdomen is rather long, its posterior margin 
being not yet twice as broad as measures the length of 
this part of the telson. The three basal joints of the ex- 
ternal antennae are, as in Petrol. mossambicus, all equally 
short. 
The left chelipede is wanting. The meropodite of the 
Notes from the Leyden Museum, Vol. XV. 
